There has been substantial research to develop powder coating paint systems. One reason for this is to eliminate the need for organic liquid carrier for the film-forming polymer which when vaporized may cause pollution problems.
As is known by those skilled in the art, with a powder coating system, particles of polymer are applied to a substrate such as by spraying. Often the particles are caused to adhere to the substrate by suitable means, such as by imparting an electrostatic charge to the particles of polymer. Afterwards, the particles of polymer are caused to coalesce by suitable means such as by baking.
One of the problems that has been encountered in existing powder coating systems is that if the particles of polymer are of low enough molecular weight that they will flow and coalesce when baked, the resulting baked paint film may not have acceptable toughness. One solution of this problem has been through the use of thermosetting powder coating systems. Such systems, however, once baked, are no longer suitable in applications requiring subsequent flow.